Spooling device assembly for hydraulic cylinder and method of assembling same

Abstract

A hydraulic cylinder assembly includes an electrical sensing device for sensing the relative position of a hydraulic piston within the cylinder. The sensor assembly includes a spool which is connected to one end of a wire that extends outside the cylinder. The spool may be rotated to take up any slack in the wire. Also, the wire is connected to a header assembly in the wall of the cylinder. The header assembly includes an internal member to which the wire is connected that does not rotate with respect to the outer header member during the threading of the outer header member into the wall of the cylinder.

What is claimed is:  
     
       1. A hydraulic cylinder assembly comprising: 
       an elongated cylinder having a cylinder wall, first and second ends and a longitudinal bore extending there through, the cylinder having an first hydraulic port at the first end of the cylinder and a second hydraulic port at the second end of the cylinder;  
       a piston mounted for reciprocating longitudinal movement within the bore of the cylinder;  
       a piston rod having a first end attached to the piston and a second end extending from and outside the second end of the cylinder, the rod being movable during reciprocation of the piston within the bore of the cylinder from a retracted position to an extended position;  
       a header assembly mounted to the cylinder wall adjacent the first end of the cylinder;  
       an electrical sensor assembly engaging one of the piston and piston rod for sensing the relative position of the piston rod as it moves between its retracted and extended positions;  
       the electrical sensor assembly having a spool with an outer cylindrical surface spaced radially inwardly from the header assembly;  
       a wire having a first end connected to the header assembly and a second end connected to the sensor assembly;  
       the spool being capable of rotation to a final position to wind any slack portion of the wire around the outer cylindrical surface of the spool;  
       mechanism engaging the spool to hold the spool against rotation after the spool is in the final position.  
     
     
       2. A hydraulic cylinder assembly according to  claim 1  wherein the cylinder wall includes a threaded opening providing communication from outside the cylinder bore to inside the cylinder bore, the header assembly comprising a first header member threaded within the cylinder bore and a second header member within the first header member. 
     
     
       3. A hydraulic cylinder assembly according to  claim 2  wherein the first header member and the second header member are capable of rotating with respect to one another so that the second header member will stay stationary during rotation of the first header member to thread the first header member into the threaded opening. 
     
     
       4. A hydraulic cylinder assembly according to  claim 3  wherein the wire is attached to the second header member whereby the wire will not rotate during rotation of the first header member to thread the first header member into the threaded opening. 
     
     
       5. A hydraulic cylinder assembly according to  claim 1  wherein the electrical sensor assembly further comprises an elongated rod and a wiper engaging the rod for sliding movement along the length thereof, the rod being stationary within the bore of the cylinder and the wiper being carried by one of the piston and rod during reciprocating movement of the piston and rod between the retracted and extended positions. 
     
     
       6. A hydraulic cylinder assembly according to  claim 5  wherein the second end of the wire is electrically connected to the rod. 
     
     
       7. A hydraulic cylinder assembly according to  claim 6  wherein the spool is attached to the rod. 
     
     
       8. A hydraulic cylinder assembly comprising: 
       an elongated cylinder having a cylinder wall, first and second ends and a longitudinal bore extending there through, the cylinder having an first hydraulic port at the first end of the cylinder and a second hydraulic port at the second end of the cylinder, the cylinder wall additionally having a threaded opening therein;  
       a piston mounted for reciprocating longitudinal movement within the bore of the cylinder;  
       a piston rod having a first end attached to the piston and a second end extending from and outside the second end of the cylinder, the rod being movable during reciprocation of the piston within the bore of the cylinder from a retracted position to an extended position;  
       a header assembly mounted to the cylinder wall adjacent the first end of the cylinder, the header assembly comprising a first header member and a second header member mounted for rotation with respect to one another, the first header member being threaded within the header opening in the cylinder wall;  
       an electrical sensor assembly engaging one of the piston and piston rod for sensing the relative position of the piston rod as it moves between its retracted and extended positions;  
       a wire having a first end connected to the second header member of the header assembly and a second end connected to the sensor assembly, whereby the first header member can be rotated for threading within the threaded opening without causing rotation of the second header member and the wire.  
     
     
       9. A hydraulic cylinder assembly according to  claim 8  wherein the sensor assembly includes a spool with an outer cylindrical surface, the second end of the wire being connected to the spool, the spool being capable of rotation to a final position for winding any slack in the wire around the outer cylindrical surface thereof, mechanism engaging the spool to hold the spool against rotation after the spool is in the final position. 
     
     
       10. A hydraulic cylinder assembly according to  claim 8  wherein the electrical sensor assembly further comprises an elongated rod and a wiper engaging the rod for sliding movement along the length thereof, the rod being stationary within the bore of the cylinder and the wiper being carried by one of the piston and rod during reciprocating movement of the piston and rod between the retracted and extended positions. 
     
     
       11. A hydraulic cylinder assembly according to  claim 10  wherein the second end of the wire is electrically connected to the rod. 
     
     
       12. A hydraulic cylinder assembly according to  claim 11  wherein the spool is attached to the rod. 
     
     
       13. A method for assembling a hydraulic cylinder assembly comprising: 
       mounting a piston and rod assembly within the bore of an elongated hydraulic cylinder having cylindrical wall for longitudinal reciprocating movement within the bore between a retracted position and an extended position;  
       mounting an electrical sensor assembly within the cylinder engaging the piston and rod assembly for sensing the position of the piston and rod assembly during movement between the retracted and extended positions, the electrical sensor assembly having a spool with an outer cylindrical spool surface;  
       attaching a header assembly to the cylindrical wall of the hydraulic cylinder;  
       attaching a first end of a wire to the header assembly and a second end of the wire to the spool;  
       winding any slack in the wire around the cylindrical spool surface;  
       holding the spool against movement away from the final position after the winding of any slack in the wire around the spool surface.